import java.util.*;

/**
 * @author LKQ
 * @date 2022/6/10 21:30
 * @description 计算字符串中含有的不同的字符的个数
 */
public class Solution {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextLine()) {
            String t = sc.nextLine();
            Set<Character> set = new HashSet<>();
            for (char c: t.toCharArray()) {
                if (c >= 0 && c <= 127) {
                    set.add(c);
                }
            }
            System.out.println(set.size());
        }
    }
}
